Examples: every shipped case and the master template write their initial condition as properties.initial_conditions.source. The wall-seeded channel and duct cases are a mean source normalized by a bulk_velocity constraint plus the generator's fluctuations.
Initial conditions (experimental): a generator may stand alone as source: {generator, params}; its velocity matches mode: generated bit for bit. project now defaults to true for every sum, as documented, including one with no generator.
Fixed: a source initial condition printed Unknown Initial Condition in the startup banner. A generator inside a source was not planned for picurv precompute, and its relative config_file and script were not resolved.